Specklefin midshipman

Where they come from

Specklefin midshipman are temperate Pacific toadfish that haunt sandy and muddy bottoms, from quiet bays out onto the continental shelf. They bury in the substrate with just the eyes showing and light up at night with tiny photophores along the body. Males are famous for humming underwater to call in females.

Setting up their tank

Think cold, quiet, and sandy. This is not a tropical fish. They like a roomy footprint, dim light, and a place to dig in. They spend a lot of time half-buried, waiting to ambush food.

• Tank size: 75+ gallons for a single adult, with at least a 4 ft x 18 in footprint.
• Temperature: 52-64 F (11-18 C). A chiller is not optional in most homes.
• Salinity: 1.023-1.026 SG; pH 8.0-8.3; low nitrate is best.
• Substrate: 2-4 inches of fine sand so they can bury without skin damage.
• Hides: PVC elbows, large smooth caves, or a flat rock forming a low-ceilinged den.
• Flow: Moderate and well-oxygenated, but leave calmer zones near the bottom.
• Lighting: Low. They are crepuscular/nocturnal and appreciate a dusk/dawn schedule.
• Lid: Tight-fitting. They can and will jump if startled.

Filtration-wise, treat them like a messy predator. A skimmer plus a decent-sized sump or canister works well. Aim a powerhead toward the surface for gas exchange, but keep the bottom calm enough that the sand does not blow around.

What to feed them

They are ambush predators that take meaty foods. Most will learn to eat from tongs. I start with something that wiggles a bit (raw shrimp tail cut into strips) and then rotate through a few items to keep nutrition balanced.

• Good staples: raw marine shrimp, squid, scallop, clam, sand lance, pieces of marine fish.
• Occasional: krill, mussel, crab legs.
• Training trick: lightly wiggle food on a feeding stick just above their burrow at dusk.

Feed 2-3 times per week. They fill up fast. Thaw frozen foods, rinse them, and offer bite-sized pieces so they do not gulp air or choke.

How they behave and who they get along with

Calm, mostly stationary, and nocturnal. They will sit buried for hours and then explode out for a meal. You might hear a faint hum at night from a content male. They are not reef safe and will eat small fish, crabs, and shrimp.

• Best setup: species-only or with other robust, temperate marine fish that are too large to swallow.
• Avoid: ornamental shrimp, crabs, snails, small gobies/blennies, and warmwater tropicals.
• Intraspecies: males can be territorial in close quarters. One per tank unless the system is very large with multiple hides.

Breeding tips

They are nest spawners. In the wild, a male claims a low-roofed space under a rock, hums to attract females, and guards the eggs stuck to the ceiling. This has been documented and managed in labs with related midshipman, but it is rarely pulled off in home tanks.

• Seasonal cues help: cool the tank through winter, then slowly raise a few degrees in spring.
• Provide a flat-roofed nest site (tile cave) and keep lighting dim and disturbances minimal.
• If they spawn, eggs will be adhesive and guarded by the male. Hatching leads to pelagic larvae that need live plankton (rotifers, copepods) and a separate rearing setup.
• Have multiple caves so the female has options and the male can choose a nest he likes.

Common problems to watch for

• Overheating: above mid-60s F, they get lethargic, breathe hard, and become infection-prone.
• Low oxygen: they are fine with moderate flow but need high O2. Aim a powerhead at the surface.
• Ammonia spikes: meaty foods rot fast. Keep up on filter maintenance and siphon leftovers.
• Refusing dead food: use tongs at dusk and add movement. Try shrimp strips or squid first.
• External scrapes: coarse gravel or sharp rocks will abrade their skin. Stick to fine sand and smooth hides.
• Wild-caught hitchhikers: deworm and quarantine 3-4 weeks before adding to your display.